Shooting for the right formula on 'Numb3rs'

Premiering 10 p.m. Sunday, the new CBS (WRDW-TV, Channel 12) series stars David Krumholtz as math genius Charlie Eppes and Rob Morrow as his older brother, Don, the FBI agent who recruits his help in solving crimes. Judd Hirsch plays their retired father.

"I love action. I've wanted to do action since I was a kid," says Morrow, probably best known as Joel Fleischman, the New York doctor forced to practice in Alaska in the '90s dramedy "Northern Exposure."

Morrow is swaddled into a flak jacket as he waits for "Action!" to be called on a scene filming in downtown Los Angeles.

Moments later, he's pulled a gun and, backed up by a SWAT team, is yelling "Do not move, FBI!" as he nabs the criminal.

As Don Eppes, Morrow needs to look comfortable handling a weapon, but he doesn't need to worry about comprehending complicated equations.

He says he's more interested now in science or math than when he was a kid, but that doesn't amount to much. "I probably know more than my character, but my character doesn't have to know a lot," he says, laughing.

On the other hand, Krumholtz as Charlie Eppes has to be quick on the draw with a piece of chalk, able to convincingly zap out intricate mathematical formulas on blackboards.

"I am not at all adept at advanced mathematics," Krumholtz says. But he's learning to be comfortable with the processes and lingo, gaining "a sense of mathematical logic that I didn't quite know I had."

He's adamant about never going into a scene "spouting mathematical concepts that I don't understand on the most base level... because one of the major things I understood about this was the scrutiny that would be placed on the actor playing the mathematician."

Krumholtz's understanding - not just of facts and theories, but also the emotional mind-set - is aided by series consultant Gary Lorden, head of the math department at the California Institute of Technology.

Lorden fixes terminology and comes up with the formulas that Charlie writes on blackboards, pieces of paper, or computers, which provide the signposts the FBI utilize to discover a serial killer's lair or the potential whereabouts of a bank robber.

Much as CBS's "CSI" shows have gone inside the science of forensics by filming exploding bullets and organ decay, the mathematical solutions of "Numb3rs" are also expanded into special effects that are visually overlaid and interjected into the plots.

Lorden describes his job as "sort of like the unseen hand holding the chalk."

At 63, his hand is too old to fill in for 26-year-old Krumholtz in close-up shots. So when that's necessary, Caltech doctoral student David Grynkiewicz provides the hand.

Most of the time, though, Krumholtz tries to do the writing himself.

"The hardest part is writing the formulas as you are speaking dialogue that you have memorized," he says.

"David is so into it," says Lorden. "He's an intense, passionate actor and I just really like and enjoy interacting with him as he's trying to get what you might call a gut level, intuitive sense of how mathematicians kind of relate to challenges, people and situations.

"I commented when I first saw how he was acting that he was in danger of making math sexy!"

Krumholtz sees Charlie as someone "very much in touch with his own sense of longing to understand the universe," a quality that makes him empathetic even to those who can't add. "He's a classic reluctant hero in that he's yet to learn how very far reaching and how truly powerful his very specific talent can be."